内蒙古特颇格日图地区大理岩的地球化学特征及成因探讨

Geochemical characteristics and genetic discussion of the marble in Tepogeritu area,Inner Mongolia

在内蒙古特颇格日图地区分布的大理岩出露于志留系徐尼乌苏组含砾砂岩或粉砂岩中,呈EW向线状断续展布,多数为似层状和透镜体状,且有相当一部分大理岩与蚀变超基性岩呈复杂的空间关系。大理岩稀土元素球粒陨石标准化配分型式为向右缓倾型,REE总量低,具弱Eu负异常。微量元素数据显示大离子亲石元素Rb,Sr,Th相对富集,高场强元素Nb,Zr等相对亏损。（87Sr/86Sr）0=0.7085~0.7100,平均0.7091。该区大理岩地质地球化学特征与沉积的碳酸盐岩相似,其原岩应为沉积型碳酸盐岩。

The marble in Tepogeritu area occurs generally in concomitantly linear layeroid bodies or lenses in the conglomeratic sandstone or siltstone of Silurian Xuniwusu formation showing complicated spatial relation with the altered ultra basic rocks.The REE chondrite-normalized distribution pattern of marble dips gently rightwards with low total REE,weak negative Eu anomaly.Trace elements are characterized by relative enrichment of LILE Rb,Sr,Th;relative depletion of HFSE Nb,Zr.The ratio of（87Sr/86Sr）0 is 0.7085～0.7100,and medium value 0.7091.It is geologically and geochemically similar to sedimentary carbonate rocks,and the original rock should be normal sedimentary carbonate rock instead of the previous carbonatite.